On 01/25/2017 06:10 AM, Steve from Tube Gauge wrote: > Hi: > > I have a CNC mill that I am considering replacing the control with LinuxCNC. > The motors are the red cap Fanuc units. I have enquired on this mailing list > about using the existing servo amps and motors. From all the replies and > help (thank you very much) I haved concluded that a good solution for me is > to remove the Fanuc encoders and amps and replace them with suitable units > that can communicate on an industry standard format. To that end I am > considering using some AMT31 programmable encoders by CUI (or other encoder > suitable for 8 pole motors) and some BE40A8 AMC amps that I have sitting on > my shelf. > > I am aware of the rpm/voltage relationship with brush DC motors. Generally, > as the voltage rises the motor rpm increases a proportional amount. How does > the voltage influence the performance of the brushless motor? The Fanuc > motors are 5S models, 126 V (DC?), 5.8A stall. The BE40A8 have a maximum > running voltage of 80 VDC. Will running the motors at the lower voltage > result in dramatically reduced performance? Will it cause other electrical > problems like an excessive rise in current demand by the motor? > > Supply voltage limits speed, current limits torque. So, running a 126 V motor on 80 V will limit you to 80/126 of the rated speed. So, if the motor is rated for 2000 RPM at 126 V, you will only get 1250 RPM. Directly driving a 5 TPI leadscrew, you would get 250 IPM linear traverse.
It will not increase the current demand of the motor at all. (That would apply to an induction motor, only.) Jon ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, SlashDot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
